| 西藏洞错地区郎山组晚白垩世火山岩的厘定——新特提斯洋北向俯冲导致增厚下地壳部分熔融的新证据 |
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| 关键词:Gerze of Tibet Late Cretaceous volcanoes New-Tethys Ocean crustal thickening plate subduction |
| 基金项目:中国地质调查局地质调查项目(编号: 121201103000150004) |
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| Identification of Late Cretaceous Volcanic Rocks of Langshan Formation in Dongco Area, Southern Tibet: New Evidence for Partial Melting of a Thickened Lower Crust Triggered by the Northward Subduction of Neo-Tethys |
| The Langshan Formation is the most representative Cretaceous formation in the Gangdise belt of Tibet. LA-ICP-MS zircon U-Pb dating of the volcanic rock (dacite) in the Langshan Formation of Dongco area, Gerze County, Tibet, was conducted based on the newly discovered volcanic intercalation in the Langshan Formation (dacite) in Dongco area, and the obtained age is (88.7±1.1) Ma, indicating that the formation of the Langshan Formation in this area should belong to the Upper Cretaceous rather than the Lower Cretaceous as previously thought. Further rock chemical analysis shows that the volcanic rocks have features similar to those of MrTak rock. Geochemical characteristics exhibit LREE enrichment and slightly negative Eu anomaly, suggesting that the northern Gangdise belt experienced significant magmatic activity in the early Late Cretaceous due to northward subduction of Neo-Tethys, which led to partial melting of thickened crust material to form Langshan Formation volcanic intercalation. The reidentification results of the stratigraphic age of the Langshan Formation and the deep tectonic features reflected by the volcanic intercalation provide a new basis for the study of the dynamic mechanism of Late Cretaceous magmatism in this region, and also indicate that it is necessary to reunderstand the regional geological and tectonic significance of the Langshan Formation in southern Tibet. |
| CI Qiong,AWANG Dan-zeng,SUOLANG Dun-dan,NI Jin-hai,WANG Xin-lu,ZHAI Jie.2021.Identification of Late Cretaceous Volcanic Rocks of Langshan Formation in Dongco Area, Southern Tibet: New Evidence for Partial Melting of a Thickened Lower Crust Triggered by the Northward Subduction of Neo-Tethys[J].Acta Geoscientica Sinica,42(1):55-62. |
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